Hybrid balancing has been used for many years to make 4-wire to 2-wire conversions, and vice versa, for duplex systems using a single line. If the balance is less than ideal, a portion of the transmitted signal will leak through the hybrid circuit into the received signal path. This is referred to as near-echo. If the near-echo is strong, compared to the received signal, more bits are required in an Analog to Digital (A/D) converter located in the receive path. The present invention relates to a technique for substantially suppressing near-echo before A/D conversion in 2-wire to 4-wire hybrid circuit.
A hybrid circuit, of the type to which the present invention relates, may be used with the invention described in our co-pending Swedish patent application Kgp152/97, which relates to the application of the present invention to extending the reach of a VDSL.